This essay explores four key dimensions of political science literature on the U.S. criminal legal system, by way of introducing articles in the special issue on criminal justice featured in the Journal of Racial and Ethnic Politics. We situate police as an institution of social control, rather than providing safety for people vulnerable to crime. The vast array of policy tools to surveil, track, and detain citizens, which lack commensurate restraints on their application, amount to a finely tuned carceral machine that can be deployed against groups newly identified as deviant. We therefore turn attention to this dynamic with our second theme: the criminalization of immigrants, the expansion of interior immigration enforcement, and the consequent targeting of Latinx people. We likewise discuss lessons for reform that can be drawn from research on representation and the political socialization that occurs as a consequence of involuntary contact with the system. We conclude with a brief discussion of directions for future research. The criminal legal system is a key force for persistent racial and class inequality. By turning attention to the politics of the criminal legal system, we forward a critical and understudied facet of American political life that intersects with all corners of the discipline. [ABSTRACT FROM AUTHOR]